1. Field of the Invention
The present invention relates to a motorcycle. More specifically, the present invention relates to a motorcycle in which a swing arm is resiliently suspended from a rear suspension via a link mechanism.
2. Description of the Prior Art
As a conventional example, a motorcycle is disclosed in Japanese Patent Application Laid-Open (JP-A) No. 2006-347472. FIG. 23 shows a vehicle body frame 300, and a swing arm 301 and a rear suspension (rear shock absorber) 302 for supporting a rear wheel of the motorcycle of the conventional example. The swing arm 301 is supported by a swing arm bracket portion 300a formed in the lower portion of the vehicle body frame 300 so as to be swingable in the up-down direction and extend rearwardly. In addition, the rear suspension 302 is vertically arranged so as to be along the substantially up-down direction, and protrudes upwardly and downwardly from the swing arm 301. An upper end 302a of the rear suspension 302 is rotatably supported by the vehicle body frame 300 in a position above the swing arm 301. A lower end 302b of the rear suspension 302 is located below the lower end of the swing arm bracket portion 300a and is connected to the lower end of the swing arm bracket portion 300a via a link mechanism 304.
The link mechanism 304 includes a substantially triangular suspension arm 310 and a tie rod 311. The suspension arm 310 has a front end rotatably coupled to the lower end of the swing arm bracket portion 300a, a rear end rotatably coupled to the lower end 302b of the rear suspension 302, and a center portion rotatably coupled to the lower end of the tie rod 311. The tie rod 311 extends rearwardly and upwardly from the suspension arm 304, and is rotatably connected to an attaching portion 301a formed on the lower surface of the swing arm 301.
As with the conventional example of FIG. 23, in the configuration in which the lower half portion of the vertically arranged rear suspension 302 protrudes downwardly from the swing arm 301, the suspension arm 310 of the link mechanism 304 is connected to the lower end of the swing arm bracket portion 302a, and the entire tie rod 311 is arranged under the swing arm 301, the lower space of the swing arm 301 and the swing arm bracket portion 300a cannot be effectively used for arranging various devices for a vehicle.
As an example of the devices for the vehicle, there is, e.g., an exhaust device. The exhaust device includes an exhaust pipe, a catalytic pipe, a collecting pipe, an exhaust chamber 306, and an exhaust muffler, and is arranged from an exhaust outlet in the front portion of an engine to the exhaust muffler in the rear portion of the vehicle. However, the lower space below the swing arm 301 and the swing arm bracket portion 300a cannot be effectively used for the exhaust device. Therefore, in the conventional example, the exhaust chamber 306 having a large volume is arranged in front of the swing arm bracket portion 300a, with the result that the length of the vehicle in the front-rear direction is increased. In addition, as the engine is arranged in front of the swing arm bracket portion 300a, the volume of the exhaust chamber 306 is limited.
In particular, in motorcycles for sports and races, the volume of the exhaust chamber 306 is required to be increased in order to cope with the exhaust gas and noise regulation in recent years, but it is difficult to cope with it.
In addition, if the exhaust chamber 306 is arranged beneath the swing arm bracket portion 300a of FIG. 23, the problem of increasing the size of the vehicle in the up-down direction arises in order to secure the minimum ground clearance of the vehicle.